Selective suppression of radiant rays.



0. F. JENKINS. SELECTIVE SUPPRESSION 0F RADIANT RAYS.

APPLICATION FILED APR. 20, 1917.

Patented May 6, 1919.

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CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRiIICT OF COLUMBIA.

SELECTIVE SUPPRESSION OF RAYS. I

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Specification of Letters Patent.

Patented May a, ram.

Application filed April 20, 1917. Serial No. 168,824.

To all tohom it may concern:

Be it known that I, CHARLES FRANCIS JENKINS, a citizen of the UnitedStates, and

.a resident of Washington, in the District'of Columbia, have inventedcertain new and useful Improvements in Selective Suppres sion of RadiantRays, of which the following is a specification reference being hadthereinto the accompanying drawing- It is often desirable to suppress.certain kinds of rays from a source of radiant energy while permittingrays of different characteristics to pass, for example, heat rays,

light rays, non-luminousrays from a source of light, and certain X rays.

Most of my work along this line has been directed to suppressing heatrays in beams of light used in projecting motion pictures. It is commonknowledge that ordinarily motion picture film ignites if the projectingbeam be allowed to'fall f0r,more than brief intervals upon the sameportion of the film. Many expedients for overcoming this evil have beentried, the beam, for example, being cooled by passing it through water,or being cut off automatically by a shutter wheneverv the advance low asafe rate.

The use of water is for many reasons objectionable,-and interrupting thebeam as 1 suggested, prevents retaining a given picture on'the'screen.while it is critically eX- amined, which is highly desirable in muchscientific and other work where motion pictures are now used. The evilsmentioned are avoided by passing the beam through a series ofsuitableplates and thereby largely suppressing the heat rays. Glassplatesreduce. heat to a considerable degree, but they break through unequalheating. Mica plates do not break, but where several are used they colora light beam. Plates of foraminous metal have neither objection. Suchplates may be of copper, which is a good conductor of heat, and may beformed by so perforating a thin sheet as to leave but a small part ofthe metal, or by weaving fine wire, or by or by spirally .body of. whichis formed of woven wire are chosen, and in the accompanying drawings,

of the film falls be Figure 1 is a plan View showing a series offoraminous plates independently and remo 'ably held in the path of apicture projecting beam of light.

Fig. 2 is an end holding devices, the plates being in position.

Fig. 3 shows one of the broad faces of one form of plate.

Fig. lis a cross section of in Fig. 3.

In these views, A represents a picture film in the path of a beam oflight from a source B which may be a common chamber containing anelectric light. C is an interposed heat reducing device which may bedetachably supported upon the chamber B, and this device includes aframe D carrying any desired number of spaced plates E transverse to andin the path of the light beam. As. shown, each plate consists of a planewire screen having a'marginal reinforcement or frame F. The frame forholding these plates, maybe of any suitable structure but in thisinstance is shown as consisting of two parallel corrugated metal sheetsin vertical planes and connected at top and bottom of each end by metalbars H, the corrugae tions forming a series of vertical groovesI theplate shown into which-the plates are dropped to rest elevation of theplate upon 'narrow in-bent portions J forming No attention need be paidto having the meshes or openings in different plates in registry oralinement. The frame having neither top nor t ottom members, air risesfreely between the plates;

What I claim is:

1. The combination with a source of light and mearis for directing abeam therefrom through free air to a screen, a series of bodies of highthermal conductivity extending across the beam and forming numerousnarrow passages through which parts of the beam may pass freely.

2. The combination with a source of light and-means for directing a beamtherefrom, of devices for holding a series of approximately parallelspaced plates across the path of the beam, and a series of foraminousplates variable at will as to number and each independently andremovably heldby a series of spaced foraminous plates of high thermalconductivity held in the path of thebeam and transmitting light raysthrough its narrow slightly separated openings.

i. For reducing heat in a beam of light, a series of spaced foraminousmetal plates all cutting the beam transversely.

5. The combination with a source of light and means for directing a beamtherefrom,

10 of a series of spaced screens of high thermal said beam, wherebylight andlheat may be varied Without varying the beam approaching thescreen.

In testimony whereof I hereunto afiix my.

signature.

.7 CHARLES FRANCIS JENKINS.

